1. Field of the Invention
The present invention relates to a method of producing brazing metals, particularly for jointing ceramic members mutually or a metallic member and a ceramic member to each other.
2. Related Art Statement
Heretofore, a jointing method using an active brazing metal has been known in a method of jointing ceramic members mutually or a metallic member and a ceramic member to each other. In this jointing method, superimposed foils of alloys containing an active metal such as Ti or Zr, or a foil of such active metal superimposed on a foil of metal such as Ni, are sandwiched between surfaces of ceramic members or surfaces of a metallic member and a ceramic member to be jointed, and heated to effect jointing of the members. For example, U.S. Pat. No. 2,857,663 and Japanese patent application publication No. 12,575/61 disclosed a brazing method wherein a foil of a Ti group metal and a foil of Cu or Ni are sandwiched and heated between surfaces of a metallic member and a ceramic member or surfaces of two ceramic members to be jointed. However, this method has the following drawbacks:
(1) The active metals that can be used as brazing metals are limited to those metals that can be easily wrought to foils, so that metals of poor ductility can not be used. PA1 (2) The foils are liable to oxidize at their surfaces, so that an alloy can not be completely formed between the active metal foil consisting of the brazing metal and other metal foil. PA1 (3) A plurality of foils are superimposed, so that, jointing of members of complicated jointing surfaces can not easily be obtained. PA1 (4) Thicknesses of the foils are varied for varying the composition of the brazing metals, so that an alloy of low alloy content can not be produced. Therefore, the brazing metals become brittle, and the joint is weak in strength. PA1 (1) In the method of preliminarily melting three metals to form an alloy, Ti content in the alloy is high, so that only a fragile alloy can be obtained, which is difficult to work in to a sheet-like ductile brazing metal. PA1 (2) In the methods of using wires, sheets or powders of the metals as raw materials, costs of processing these raw materials are so expensive that practical use of the methods is not economical.
U.S. Pat. No. 4,471,026 disclosed ternary alloy solders consisting of Cu, Ti and a metal selected from Ag, Au, Sn or In for brazing ceramic members mutually, which also disclosed methods of producing the solders by preliminarily melting three metals to form an alloy thereof, knitting three metals wires to form a strand, superimposing three metal sheets, or mixing three metals powders. However, these methods also have the following drawbacks:
U.S. Pat. No. 4,486,386 specification disclosed Pd-Au alloy solder containing at least one of Ti, V and Zr. However, it has disadvantages that special melting such as vacuum melting or the like is necessary for melting active metals such as Ti, V and Zr, and that the obtained alloys are difficult to work.
Japanese patent application laid-open No. 81,071/85 disclosed a metal sheet for jointing ceramic members, wherein a layer of brazing metals is coated with a layer of an active metal. However, this sheet has a shortcoming that the thickness of the active metal layer is too large as compared to the thickness of the brazing metals layer, so that a joint of satisfactory strength can not be obtained.